Effects of LiF additive on crystal structures, lattice vibrational characteristics and dielectric properties of CaWO4 microwave dielectric ceramics for LTCC applications
Effects of LiF additive on crystal structures, lattice vibrational characteristics and dielectric properties of CaWO4 microwave dielectric ceramics for LTCC applications
复制标题
LiF添加剂对LTCC应用CaWO4微波介电陶瓷晶体结构、晶格振动特性和介电性能的影响
DOI：
10.1016/j.ceramint.2022.06.259
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发表时间：
2022-06
影响因子：
5.2
通讯作者：
Kaixin Song
中科院分区：
文献类型：
--
作者：
Zhongfen An;Jiqing Lv;Xiangyu Wang;Yue Xu;Lingcui Zhang;Feng Shi;Hai Guo;Di Zhou;Bing Liu;Kaixin Song
本文采用固相反应法制备了CaWO4-xwt.%LiF(x=0.5-3.0)微波介质陶瓷，结合X射线光电子能谱和扫描电子显微镜的测试结果，所有的X射线衍射峰都归属于CaWO4。结果表明，LiF在高温下形成液相，以非晶态存在，CaWO4-xwt.%LiF样品属于复相陶瓷。随着LiF含量的增加，液相填充了陶瓷的气孔，提高了陶瓷的致密性。因此，品质因数从59,055 GHz(x=0.5)增加到77,855 GHz(x=3.0)，介电常数从9.26(x=0.5)下降到8.41(x=3.0)。用拉曼光谱和红外光谱研究了CaWO4-xwt.%LiF样品的晶格振动特性。四参数半量子(FPSQ)模型的拟合结果表明，与Ca-O键振动相关的外模对介电响应的影响最大。此外，模拟的本征性质与实测值基本吻合。当x值增大时，介电常数随键长的减小而减小。品质因子与Bg模的半高宽呈负相关，与堆积分数呈正相关。CaWO4-3wt.%LiF样品在850℃时与银粉具有良好的相容性，在低温共烧领域具有较高的应用价值。
In this paper, CaWO 4 - x wt. % LiF ( x = 0.5–3.0) microwave dielectric ceramics are prepared by conventional solid-state reaction at 850 °C. All the X-ray diffraction peaks are attributed to CaWO 4 , combined with the results of X-ray photoelectron spectroscopy and scanning electron microscope. They indicate that LiF forms liquid phase at high temperature, exists in amorphous phase, and the CaWO 4 - x wt. % LiF samples belong to the composite ceramics. With the increase of the LiF content, the liquid phase fills the pores of the ceramics and increases the compactness. Therefore, the quality factor increases from 59,055 GHz ( x = 0.5) to 77,855 GHz ( x = 3.0), and the dielectric constant decreases from 9.26 ( x = 0.5) to 8.41 ( x = 3.0). The lattice vibration characteristics of the CaWO 4 - x wt. % LiF samples are studied by Raman and infrared spectroscopy. The external modes associated with the vibration of the Ca–O bonds have the greatest influence on the dielectric response, as shown by the fitting results based on the four-parameter semi-quantum (FPSQ) model. In addition, the simulated intrinsic properties and measured values are in general agreement. When the x value increases, the dielectric constant decreases with the decrease of the bond length. The quality factor has a negative correlation with the FWHM value of the B g mode and a positive correlation with the packing fraction. Finally, the CaWO 4 -3 wt.% LiF sample has good compatibility with the silver powders at 850 °C, and high application value in the LTCC field.